The invention relates generally to an apparatus for delivering optical energy and, in particular, to a handheld apparatus configured to conduct resurfacing or other cosmetic treatment of skin with optical energy.
Optical energy, particularly laser energy, is commonly used as a versatile tool in medicine to achieve desired outcomes in a tissue that is treated. For example, lasers and other forms of intense light have been used to treat common dermatological problems such as hypervascular lesions, pigmented lesions, acne scars, rosacea, and/or for hair removal. Forms of optical energy are also used for cosmetic purposes, to achieve a better cosmetic appearance by resurfacing the skin, by remodeling the different layers of skin to improve the appearance of wrinkled or aged skin, and/or by tightening the skin.
Generally, skin resurfacing is understood to be the process by which the top layers of the skin are completely removed using chemicals, mechanical abrasion or optical energy in order to promote the development of new, more youthful looking skin and stimulate the generation and growth of new skin. In laser skin remodeling, laser energy penetrates into at least a portion of the deeper layers of the skin and is aimed at stimulating the generation of and/or altering the structure of extra-cellular matrix materials, such as collagen, that contribute to the youthful appearance of skin.
During dermatological tissue treatment utilizing optical energy, a light beam irradiates the skin surface of a patient. Generally, lasers that are used for such treatment operate at a wavelength that is absorbed by one of the natural chromophores in the skin, such as water. If water is the primary chromophore, cellular and interstitial water absorbs light energy and transforms the light energy into thermal energy. The transport of thermal energy in tissues during treatment is a complex process involving conduction, convection, radiation, metabolism, evaporation and phase change that vary with the operational parameters of the light beam. These laser-based procedures should not damage the tissue underlying or surrounding the target tissue area.
The light beam optical operational parameters, such as wavelength, power, the intensity of the light, pulse duration, rate of emission, etc. may be selected to heat the cellular and interstitial water in a patient's skin, which causes temperature increases that produce a desired dermatological effect. Conversely, improper selection of the optical operational parameters can result in undertreatment or overtreatment of the tissue. Therefore, the optical operational parameters used in the treatment should be accurately controlled so that the light is delivered to the tissue with the proper fluence and in a uniform, controllable manner. A variety of devices have been proposed that intelligently control laser beam power, intensity, duration, etc. However, as will be discussed in greater detail below, application of these devices have significant disadvantages.
Known devices for dermatological tissue treatment include a hand-held delivery apparatus, sometimes referred to as a handpiece. A handpiece is the preferred means by which physicians apply treatment to tissue. During treatment, the handpiece emitting light is moved by a physician or health care professional's hand along the tissue to be treated. Treatment level from such a device is typically set in advance by manually selecting one or more light beam operational parameters. The operational parameters, which for example include power level, energy, pulsation rate, temperature, light intensity, current, etc., determine the degree of treatment of the entire treatment process.
One disadvantage of some of the existing handpiece apparatuses is that they require strict precision in positioning of the handpiece and application of controlled movement in order to stay within limits of uniform and efficacious treatment. Theoretically, strict precision can be achieved with a high degree of skill, attention and dexterity from the treating physician. In a real procedure, however, manual application and control of the handpiece can easily result in non-uniformity of treatment due to imprecise or involuntary movements of the human hand and/or uneven tissue surfaces. This often results in either some areas of the targeted tissue being under-treated, or causes some areas to be over-treated.
Consequently, a typical method of using conventional handpieces to deliver an optical energy based treatment is to produce a macroscopic, pulsed treatment beam that is manually moved from one area of the skin to another in a patchwork-like or stamping manner (i.e., the handpiece is not in continual motion when the treatment beam is applied) in order to treat a larger portion of tissue. Such an approach can have the disadvantage of producing artifacts and sharp boundaries associated with the inaccurate positioning of the individual treatments with respect to the treated skin surface.
Increasingly, conventional bulk skin treatment methods are being replaced by fractional treatment methods, as the use of fractional treatment methods has been found to produce fewer and less severe side effects than conventional bulk treatment methods, such as, for example, reduced damage to the epidermal layers of the skin. Fractional treatment methods involve the generation of a large number of relatively small treatment zones within a portion of tissue. The optical energy impacts directly on only the relatively small treatment zones, instead of impacting directly on the entire portion of tissue undergoing treatment, as it does in conventional bulk treatments. Thus, a portion of skin treated using a fractional optical energy treatment method is composed of a number of treatment zones where the tissue has been treated directly by the energy, contained within a volume of tissue that has not been treated directly by the energy. The treatment can, for example, produce coagulation and/or necrosis of tissue. Fractional treatment methods make it possible to leave substantial volumes of tissue untreated (e.g., uncoagulated and/or viable) within a portion of tissue that has been treated.
Devices which are capable of providing fractional treatments sometimes employ a stamping means as discussed above for delivering optical energy. Other devices employ means to scan one or more beams of optical energy across a portion of tissue, or a means to divide one or more beams of optical energy into a plurality of beams, and deliver the plurality of beams to a portion of tissue to be treated as the handpiece is moved. These additional scanning or dividing components are often located in the handpiece, making the handpieces for fractional scanning treatment devices more complex than the handpieces for bulk treatment devices and stamping treatment devices.
Complex handpieces, such as those that deliver uniform, controlled treatments while in motion can require the use of high manufacturing tolerances and/or the use of great precision when connecting the optical components of the handpiece as well as the rest of the device in order for the components of the device to function properly and for the device to deliver the optical energy in an efficient, effective, uniform, and controlled manner. For example, a large number of functional parameters need to be properly set in order for an optical energy system and/or source to function properly on its own. Similarly, a large number of functional parameters need to be properly set in order for a handpiece and its optical energy delivery system (e.g., scanner, lens array, or other means for delivering the treatment beam(s) to the portion of tissue) to function properly on their own, as well as to function properly in conjunction with an optical energy system and/or source. This inherent complexity has typically prevented such handpieces from being cost-effective to manufacture for home use by a non-physician consumer.
Therefore, an improved handpiece for dermatological treatment conducted by a non-physician consumer that addresses at least some of the shortcomings of conventional handpieces is desirable.